The objectives are to clarify the details of the behavior of the hemoglobin system, and to find which of the models discussed in the literature better explains the system. Crucial to this appears to be the relationship between ligand binding and conformational changes in hemoglobin. It is proposed to measure the correlations between the fractional saturation with ligands and a) the sedimentation velocity of the system, b) the number of protons liberated by the complex Hemoglobin-organic phosphate. Related to this is the investigation of the acid base behavior of the interaction of deoxyhemoglobin with organic phosphate, and a study of the bands of absorption of the light in the visible region and in the Soret region for the hemoglobin system. Also proposed are chemical modifications of various hemoglobins in those groups which appear to be related to the Bohr effect or to the binding of organic phosphate.